Multihomed BGP to internet - use only 1 path inbound

[carl_townshend]

Hi All

We have a multihomed internet connection to 2 different ISPs.

We want traffic to only come inbound on one of the links.

What is the best way to achieve this? as-path prepend on the one we least prefer? or use the bgp conditional advertisement feature?

If we did use the conditional advertisement feature, how would we configure this? we have 2 routers, IBGP between them and just learning a default from each provider.

cheers

[paul driver]

Hello @carl_townshend 

@carl_townshend wrote:

 is there no way other than prepending to do this? I thought conditional advertisement could solve this ?

Can you share a topology diagram please, what you do not want under any circumstance is for you wan rtrs to become a transit path between ISPs

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As I have stated you defiantly need to beware you do not become a transit path for ISPs, however the most simplistic solution depending on how may routes you need to advertise and WITHOUT using as-path prepending I would say (my own opinion) is to advertise your network towards the less preferred ISP with aggregated routes and advertise the more specific routes to the preferred ISP, its not a elegant as say As-Path prepending but it would work.